Means for controlling electrically-operated driving systems.



J. G. MAGFARLANB, H. BURGE & A. WILLIAMS.

MEANS FOR CONTROLLING ELEGTRIGALLY OPERATED DRIVING SYSTEMS.

APPLICATION FILED DEC. 22, 1911.

1,019,676. Patented Mar. 5, 1912.

VZZLG 5662' 221067160219 I m I 2 UNITED STATES PATENT orFIoE.

J'AHES COL Q'UHOUN MACFABLANE AND HARRY BURGE, OF OHELHSFORD, AND ALAN WILLIAMS, OF LONDON WALL, LONDON, ENGLAND, ASSIGNOBSTO CROEPTON & COMPANY, LIMITED, 01 CHELMSFORD, ENGLAND.

MEANS FOR CON TROLLING ELECTBICALLY-OPERATED DRIVING SYSTEMS.

Specification of Letters Patent.

' Patented Mar. 5, 1912.

Application filed December 22, 1911. Serial 1T0. 867,387.

To whom it concern:

Be itknown that we, JAMES CoL UHoUN MAorAnnANn and HARRY Boson, residing at Arc Works, Ghelmsford, in the county of Essex, England, and ALAN WILLIAMS, residing at Salisbury House, London Wall, London, England, all subjects of the King i of Great Britain, have invented certain new and useful Im rovements. in Means for Controlling Electrically-Operated Driving This invention relates to controlling de-' vices for use in connection with electriwith this invention the cally-operated driving systems wherein wide variations in torque and speed occur.

while the demand for ower from the supobject to provide an improved braking gear and safety gear, for use in such systems.

Electrically-operated hauling or winding machinery possesses the characteristics above referred to, and the invention will be hereafter described, byway of example, in connection-therewith. Y

In an electrically-operated hauling or windin system arranged in accordance hauling or winding motor is supplied with energy from a direot current generator provided with a variable field excitation so that it is capable of delivering current tosaid hauling or winding motor at any voltage from zero to a mam'minn voltage. In this instance the field; of the said generator is however not reversible "and. a reversing switch is therefore inserted in the main circuit "for reversing thezdirection of rotation of the working-motor. But in cases where the load is excefition'ally heavyas for example in electrics y-driven rolling-mill plants,

the generator or other field may be reversible and said reversing switch in the main circuit may be replace by compound reversing switches acting on such fields as may require hereinafter called the brake motor. The

armature of said brake motor is capable only of the limited rotation necessary to move the brake into its .ofi position, and may be traversed by the main current, and the field of said brake motor which is of a fine wire type may be excited. from the brushes of t e exciter of the main generator, or vice versa. A brake of this ty e has certain advantages; it only allows t e haula e gear to rotate freely when the current owing through the armature of the brake -motor is in the forward direction.

If there is any tendency for the motors to regenerate, that is to say to return current to the line, the torque setup by the brake motor will act in the same sense as the spring'or weight and will tend to apply the brake harder than before. 'lthis arrangement not only effectually prevents the cage from descending at an excessive s eed but alsois of great value in cases in w ich the direct current generator is driven by a motor drawingpower from an electrical circuit or from a mechanical prime mover,

because under these conditions the return of ower to such circuit or prime'mover may be undesirable. A 4 further advantage or this form of electric brake is that on fairure of either the main current or the en citin current-the brake is at once applied. In t is instance the regulation of the mo= tors is obtained by varying the excitation of the generator from zero to a maximum, butthe motors are reversed by. reversing the main current. In order that the reversal of the main current may not take place when the switch is carrying aheavy current the following safety device is adopted. The controller handle is not directly connected to the contact lever of the gen lo 015 being withdrawn connecting the hand lever to the cont-act lever is included in the same circuit which excites the aforesaid brake motor and in said circuit is arranged a makeand break switch such that this circuit is broken prior to the opening of the main circuit or other reversing switch. The operation of the reversing switch therefore entails the previous denergizing ofboth the brake motor and the said electr c-magnet so that before the main current or the necessary field circuits can be reversed, the brake will be applied and the contact lever controlling the field of the generator will be released and will return to zero, thus causing the generator to lose its excitation. A further safety device to prevent overwinding is inserted in the said circuit. If the cage is overwound in one direction the effect is to break the local circuit which applies the brake and causes the generator to lose its excitation, and the said circuit cannot be reestablished and the generator reexcited until the reversing switch has been thrown over so as to produce a reverse motion of the cage.

The accompanying drawings illustrate d1- agrammatically and by way of example, a haulage or winding system arranged according to this invention.

- A is the stator and B is the rotor of a three-phase alternating current electric motor direct coupled to the armature G of a direct current generator.

M is the working motor connected to the brushes ofthe generator Gr through the re-' versing switch S brake motor K.

The generator G is provided with a separately excited field winding F whereof the excitation is produced by the exciter E or other suit-able source, a variable hand controlled resistance R bein inserted in the circuit thereof operated in the well-known manner by a magnetically controlled contact lever L. The armature K of the brake motor is connected mechanically to the and the armature of the brake P on the cage or winding drum D in such a way that while the weight W applies the brake,'the torqueexerted by the armature K when traversed by a current in thepositive direction will overcome the eftect of the weight W and take 05 the brake P. The contact lever L is maintaind normally in the zero position of no excitation (as shown on the drawing) by the spring N and hand lever H makes connection therewith by means I of the electro-magnet i so that when said electro-magnet is deenergized, the lever L will swing back to the zero position of no excitation from which position it cannot again be moved until the said electro-mag net has again been energized.

The electro-magnet i and the fine wire field winding f of the brake motor K are energized from the exciter'E and in such circuit is included a two-way pilot switch T operating by the handle of the reversing switch S by means of a mechanical connection S, so that when the reversing switch is in position for hauling as shown in the diagram the pilot switch '1 makes contact when the cage is overwound in ward directlon.

with a contact a and when the switch S is in position for lowering said pilot switch makes contact withthe contact c is a switch which is opened on the cage being overwound in the upward direction, and (Z is a switch which is opened tpositively e down- When the cage is ascending the circuit under consideration leads from the ,exciter brush through the electro-magnet 2' and through the field winding f of the brake motor K thence through the pilot switch T and the switch 0 back to the exciter. When the cage is descending the circuit is the same, with the exception that the current traverses the switch (2 instead of the switch 0, and the contact 5 instead of the contact a. The efi'ect of this arrangement is as follows :If the excitation or the winding motor circuit fails or the motors are overwound in either direction, the brake is applied, the lever L returns to its zero position and if overwindin has occurred connection cannot be reestabllshed between the handle H and the lever L until the reversing switch not limited in its application to hauling or winding machinery, but may be utilized in connection with numerous other electrically operated driving systems having the characteristics set out above.

What we claim is 1. An electrically-operated driving system comprising a driven generator, adrivin motor, mains carrying current from sai driven generator to said driving motor, a variable separate excitation to said generator, a mechanical brake, a direct current brake-motor, said brake being normally on and being pulled ofi by said direct current brake-motor, the armature of said brake motor being connected in series with said driven generator, the field of said brake motor being excited from the same source of excitation as said generator.

2. m1 electrically-operated driving system comprising a driven generator, a drivin motor, mains carrying current from sai driven generator to said driving motor, a variable separate excitation to said generator, a mechanical brake, a direct current its brake-motor, said brake being normally on and being pulled off by said direct current brake-motor, said brake motor having an armature and a field one of which elements is connected in series with the driven generator and the other lement being connected to the said source of excitation for the generator.

3. An electrically-operated driving system comprising a driven generator, a drivin motor, mains carrying current from sai driven generator to said driving motor, a variable separate excitation to said generator, a mechanical brake, a direct current brake-motor, said brake being normally on and being pulled ofi by said direct currentbrake-motor, the armature to said dlre ct current brake-motor being connected in series with said driven generator, the field to said direct current brake-motor being ex cited from the same source of excitation as said generator, an electro-magnet in series with said field of said direct current brakemotor, an operating handle, a voltage control lever, said electro-magnet connecting said operating handle to said voltage control lever, a pilot switch in series with the field of said direct current brake-motor, and overwinding switches also in series with the field of said direct current brake-motor.

4. An electrically-operated driving system comprising a driven generator, adriving motor, mains carrying current from said driven generator .to said driving motor, a 9

variable separate excitation to said generator, brake-motor, said brake being normally on and being pulled off by said direct current brake-motor, said direct current brake-motor having an armature and a field, one of said elements being excited from the same source of excitation as said generator, and the other element of the brake motor being connected in series with said driven generator, an electro-magnet in series with one of said elements of said direct current brake-motor, an operating handle, a voltage control lever, said electromagnet connecting said operating handle to said voltage control lever, a pilot switch in series with the other element of saiddirect current brake-motor, and overwinding switches also in series with the armature of said direct current brake-motor.

In testimony whereof we have hereunto set our hands in presence of two subscribing witnesses.

JAMES GOLQUHOUN MAGFARLANE. HARRY BURGE.

ALAN WILLIAMS. Witnesses:

NEVILLE E. BROOKES,

ERNEST JOHN HILL.

a mechanical brake, a direct current 

